Behavioral Response Assessment
Objective: Identify the afferent neural pathway mediating emotional responses to acoustic stimuli by comparing effects of lesions in auditory cortex versus medial geniculate nucleus on conditioned emotional responses
Gather these items before starting the experiment. Check off items as you prepare.
Equipment3
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Protocol Steps
Neuroanatomical tracing to identify auditory cortex
Anterograde neuroanatomical tracing studies were conducted by injecting HRP into the medial geniculate nucleus to define the rat auditory cortex
Note: This tracing study was performed prior to lesion placement
View evidence from paper
“The rat auditory cortex was defined through anterograde neuroanatomical tracing studies involving the injection of HRP into MG”
Lesion placement
Lesions were placed in either the auditory cortex or medial geniculate nucleus (MG), or in the inferior colliculus as a control
Note: Different groups received lesions in different brain regions for comparison
View evidence from paper
“Lesions were then placed in the auditory cortex or in MG”
Recovery period
Rats were allowed to recover following lesion surgery before behavioral testing
Note: Recovery period was necessary before fear conditioning trials
View evidence from paper
“After 10 to 20 days the rats were subjected to classical fear conditioning trials”
Classical fear conditioning
Rats underwent classical fear conditioning trials involving pairing of a pure tone with electric footshock
Note: This establishes the acoustic conditioned emotional stimulus
View evidence from paper
“the rats were subjected to classical fear conditioning trials involving the pairing of a pure tone with electric footshock”
Extinction trials with measurement
During extinction trials (no footshock), the acoustic conditioned emotional stimulus was presented while measuring autonomic and behavioral responses
Note: Measurements included mean arterial pressure, heart rate, freezing duration, and drink suppression
View evidence from paper
“Changes in mean arterial pressure and heart rate and the duration of immobilization (freezing) and drink suppression elicited by presentation during extinction trials (no footshock) of the acoustic conditioned emotional stimulus were measured”